The present disclosure herein relates to a polarization controller.
As the rapid development of computer and internet technologies in the information society, there is a demand for techniques for quickly processing various types of large-volume information. Existing technologies, which rely on electronic technology based on a copper wiring, are limiting in terms of the throughput and speed. To meet the demands of the high-speed information communication society, it is essential to develop optical transmission technologies that accommodate a large amount of information capacity.
The high-speed information communication systems using coherent technologies in the development of optical communication technologies are being developed from the existing (on-off keying) direct amplitude modulation manner, in which a light intensity is modulated, to a phase shift keying (PSK)-phase modulation manner, in which a phase of an optical signal is modulated or a manner in which the phase and the light intensity are modulated at the same time. The coherent optical communication technologies may use transverse electric (TE)/transverse magnetic (TM) light, which is orthogonal to polarization of a signal, in addition to phase components of the optical signal. In a polarization multiplexing manner that is one of the coherent optical communication technologies, the TE light and the TM light may be independently modulated and then combined with each other to transmit light. Thus, data may be doubly expanded in capacity. Also, in the coherent optical communication technologies, a polarization modulation manner of modulating a polarization state to transmit a signal, such as modulating the intensity and phase of light, is also applicable.